You can buy a Coanda intake screen online for under $500. It arrives in a box, pre-built in 304 stainless steel, with a fixed 1.5 mm slot width, a 5-degree wire tilt, a single standard dimension, and a rated flow of 6 litres per second.
For a do-it-yourself (DIY) micro-hydro system powering a remote cabin, that screen may work perfectly.
For a 200 l/s municipal water diversion, a snowmaking system feeding 30 snow guns at 2,000 metres elevation, or a hydropower intake that must meet eel protection regulations in a brackish estuary: that same screen is not just inadequate. It will fail.
A Coanda screen is not a standard mass-produced product like a pipe fitting or a filter cartridge. It is a hydraulic device whose performance depends entirely on the match between its design parameters and your specific site conditions. The slot width, wire tilt angle, screen curvature, acceleration plate shape, material grade, array configuration, and anti-icing measures must all be calculated for your flow rate, available head, water chemistry, debris type, fish protection requirements, and climate.
This guide explains the difference between pre-built, fixed-size screens sold off the shelf for the DIY micro-hydro market and custom Coanda screens, shows you when each is appropriate, and explains ADENCO's project-specific engineering process step by step.
Table of Contents
- What Pre-Built Coanda Screens Offer
- Where Pre-Built Screens Fall Short
- What a Custom Coanda Screen Delivers
- When a Pre-Built Screen Is Enough
- When You Need Custom Engineering
- ADENCO's 6-Step Custom Design Process
- What Custom Engineering Costs, and What It Saves
- Frequently Asked Questions
- References
What Pre-Built Coanda Screens Offer
Several manufacturers sell pre-built Coanda screens in fixed sizes, primarily targeting the DIY micro-hydro market. These are typically:
- Fixed dimensions: one or two fixed panel sizes (e.g., 380 mm × 380 mm)
- Fixed slot width: usually 1.5 mm or 2.0 mm
- Fixed wire tilt: standard 5 degrees
- Single material: 304 stainless steel
- Low rated capacity: typically 6–17 l/s per panel [1]
- No acceleration plate optimization: generic or user-fabricated acceleration plate with an ogee-shaped (S-curved) profile
- No anti-icing equipment
- No hydraulic analysis: the user must determine if the screen matches their site
Pre-built screens are affordable ($200–$750 per panel), ship quickly, and work well within their intended operating range. They have enabled hundreds of small DIY hydro systems worldwide [2].
Where Pre-Built Screens Are Not Enough
The limitations of pre-built screens become apparent when any project parameter falls outside that narrow operating range.
Flow Rate Mismatch
A pre-built panel rated at 6–17 l/s works for a small watercourse diversion. But most professional applications require 50–2,000+ l/s. Stacking multiple pre-built panels does not solve this: the weir geometry, acceleration plate shape, and collection chamber must be designed as an integrated system, not assembled from modular parts [3].
Wrong Material for the Water
Pre-built screens are typically 304 stainless steel. If your raw water has chloride above 200 ppm (coastal rivers, estuarine sites, brackish groundwater, or locations downstream of road salt application) 304 will corrode. The screen needs to be specified in 316L, duplex 2205, or higher grade based on water chemistry analysis [4][5]. Pre-built products do not offer this choice.
Slot Width Not Matched to Requirements
A fixed 1.5 mm or 2.0 mm slot may be too wide for fish protection compliance (UK Eels Regulations require 1.0 mm in estuarine zones [6]) or too narrow for maximum flow capacity in applications without fish protection requirements. The slot width should be an engineering decision determined by site-specific biology and regulatory requirements: not a manufacturing default.
No Acceleration Plate Engineering
The acceleration plate is not optional: it is a critical hydraulic component that determines how water is delivered to the screen surface [3][7]. The correct shape of the acceleration plate depends on the weir height, crest geometry, and design flow. A mismatched acceleration plate causes flow separation, turbulence at the screen entry, reduced capacity, and impaired self-cleaning. Pre-built screens either omit the acceleration plate entirely or include a generic shape that may not match your weir.
No Anti-Icing Capability
Pre-built screens have no equipment for cold-climate operation. For any site where water or air temperatures approach freezing (which includes virtually all snowmaking, most hydropower, and many municipal intakes in northern latitudes) the screen requires integrated anti-icing engineering [8][9].
No Regulatory Documentation
Professional projects require engineering documentation: hydraulic calculations, material certificates, dimensional tolerances, and fish protection compliance data. Pre-built products come with a product sheet, not an engineering package.
What a Custom Coanda Screen Delivers
A custom-designed Coanda screen is designed for one specific project, at one specific site, with one specific set of operating conditions. Every parameter is calculated rather than taken from a default value:
| Parameter | Pre-Built | Custom |
|---|---|---|
| Screen width | Fixed (one or two sizes) | Calculated from design flow and site geometry |
| Screen length | Fixed | Optimized for the balance between flow passing through the screen and head loss |
| Slot width | Fixed (1.5 or 2.0 mm) | Selected for fish protection + debris + water quality |
| Wire tilt angle | Fixed (5°) | Optimized for capacity vs. filtration balance (3°–7°) |
| Material grade | 304 only | 304, 304L, 316, 316L, duplex, or super duplex per water chemistry |
| Acceleration plate | Generic or none | Shape calculated for the site-specific weir geometry |
| Screen curvature | Fixed radius | Radius optimized for the available head and flow conditions |
| Anti-icing | None | Integrated system matched to climate conditions |
| Array configuration | Single panel | Multi-panel arrays with shared collection system |
| Engineering documentation | Product sheet | Full hydraulic analysis, material certificates, compliance data |
When a Pre-Built Screen Is Enough
Pre-built Coanda screens are a good choice when all of the following are true:
- Flow requirement is below 20 l/s
- Water is clean freshwater (chloride <200 ppm)
- No fish protection regulations apply
- No freezing conditions during operation
- The weir already exists and has adequate available head (>450 mm)
- No engineering documentation is required by the permit authority
- The user has the hydraulic knowledge to design the concrete structures (weir, collection chamber, bypass)
This describes a typical DIY micro-hydro system or small farm water diversion, and for these projects, a pre-built screen is practical and cost-effective.
When You Need Custom Engineering
You need a custom-designed Coanda screen when any of the following are true:
- Flow rate exceeds 20 l/s: Multi-panel arrays require integrated hydraulic design
- Fish protection regulations apply: Slot width must be checked to match species-specific requirements
- Water contains chloride >200 ppm: Material grade must be matched to water chemistry
- Freezing conditions are possible: Anti-icing equipment is essential
- The project requires official permits: Engineering documentation, compliance certificates, and hydraulic calculations are needed
- The weir must be designed or modified: Acceleration plate shape must match the specific weir geometry
- The application is critical (Municipal water supply, snowmaking (revenue-dependent), hydropower (revenue-dependent)) where screen failure has financial or safety consequences
- Unusual site constraints: Limited weir width, very high or very low available head, high sediment load, variable flow range, or retrofit of existing infrastructure
In practice, this means every professional and commercial project requires custom engineering. The question is not whether to customize, but how much engineering is needed.
ADENCO's 6-Step Custom Design Process
Step 1: Site Data Collection (Day 1)
You provide the essential site parameters, or ADENCO's engineering team helps you determine what data is needed:
- Design flow rate (peak and minimum)
- Available head (gross and minimum operating)
- Description of the water body and water chemistry (chloride, pH, temperature range)
- Fish species and life stages present (if applicable)
- Regulatory requirements
- Climate conditions (air and water temperature range, ice risk)
- Site photographs and dimensional constraints
Step 2: Hydraulic Analysis (Days 1–2)
ADENCO's engineers perform the hydraulic design using the US Bureau of Reclamation (USBR) Coanda Design Guide (Wahl, 2003, report R-2003-03) [3] and our sizing tools calibrated on operating data from installed screens. This analysis determines:
- Optimal screen width and length for the design flow
- Slot width selection based on fish protection and water quality requirements
- Wire tilt angle optimization for the balance between capacity and screening fineness
- Acceleration plate shape matched to the weir geometry
- Screen curvature radius
- Head loss verification at minimum and maximum operating conditions
- Bypass flow calculation
Step 3: Material and Treatment Specification (Day 2)
Based on water chemistry data, the engineering team selects:
- Stainless steel grade (304L, 316L, duplex, or super duplex)
- Surface treatment (pickling and passivation as standard, plus any specialized coatings)
- Anti-icing system type and configuration (if required)
- Support structure material
Step 4: Design Review and Approval (Days 2–3)
ADENCO delivers a complete design package for your review:
- General arrangement drawing with dimensions
- Hydraulic performance summary (flow vs. head curve)
- Material specification sheet
- Fish protection compliance statement (if applicable)
- Anti-icing system specification (if applicable)
- Quotation with delivery time
You review, request modifications if needed, and approve the design.
Step 5: Manufacturing and Quality Control (2–4 Weeks)
The screen is manufactured at ADENCO's facility with full quality control:
- Wedge wire panel fabrication to specified slot width (±0.1 mm tolerance)
- Acceleration plate formed to the calculated shape
- Support structure fabrication and assembly
- Anti-icing integration (if specified)
- Dimensional inspection of every panel
- Hydraulic test verification (for critical applications)
Step 6: Delivery and Installation Support
ADENCO delivers the completed screen assembly with:
- Installation guide specific to your site configuration
- Detailed general arrangement and connection drawings
- Material certificates and test reports
- Engineering documentation package for regulatory submission
- Remote or on-site installation support as needed
Total time from initial inquiry to delivery: typically 3–6 weeks, depending on screen complexity and anti-icing requirements.
What Custom Engineering Costs, and What It Saves
Custom engineering adds cost compared to a pre-built screen. The question is whether that cost is justified by what it prevents.
What Custom Costs
- Engineering analysis and design review: included in ADENCO's quotation (no separate engineering fee)
- Custom screen panels: typically 20–40% more than pre-built panels of equivalent size, depending on material grade and slot width
- Anti-icing integration: adds 15–30% to screen assembly cost (when required)
- Engineering documentation package: included in ADENCO's quotation
What Custom Saves
| Risk Avoided | Typical Cost of the Mistake |
|---|---|
| Wrong material → corrosion failure | Full screen replacement, plus downtime |
| Undersized screen → insufficient flow | Additional panels + modification of the concrete structures mid-project |
| Wrong slot width → regulatory non-compliance | Screen replacement + project delay (4+ months typical) |
| No anti-icing → winter shutdown | Lost revenue for every winter shutdown, depending on the application |
| Poor acceleration plate → reduced capacity | Screen delivers 40–60% of expected flow; requires redesign |
| No hydraulic analysis → mismatch with the available head | Screen operates at fraction of design capacity; weir modification required |
Every one of these failures has occurred on real projects where a pre-built screen was specified instead of a custom design. The cost of custom engineering is a fraction of the cost of any single failure.
Frequently Asked Questions
Can I get a custom Coanda screen designed for my project?
Yes. ADENCO specializes in project-specific Coanda screen engineering. Every screen we deliver is designed for your exact site conditions: flow rate, available head, water chemistry, fish protection requirements, climate, and physical constraints. There is no minimum project size; we design screens from small irrigation diversions to large multi-panel arrays for municipal water supply.
How long does custom Coanda screen design take?
The engineering design typically takes 2 business days from receipt of site data. Manufacturing takes 2–4 weeks depending on screen size and complexity. Total lead time from inquiry to delivery is typically 3–6 weeks.
Is custom engineering more expensive than buying a pre-built screen?
Custom screen panels typically cost 20–40% more than equivalent-size pre-built panels. However, ADENCO includes all engineering analysis, hydraulic calculations, design documentation, and installation support in the quotation at no additional engineering fee. The cost of custom engineering is a fraction of the cost of replacing a wrong screen, modifying concrete structures, or losing production to a preventable failure.
What information do I need to provide for a custom design?
At minimum: design flow rate (peak), available head, type of water body and water chemistry, and site dimensions. Ideally also: fish species present, applicable regulations, climate conditions (temperature range, ice risk), and site photographs. If you are unsure about any parameter, ADENCO's engineering team can help you determine what data to collect.
Do I need a custom screen for a small project?
For DIY micro-hydro systems under 20 l/s in clean freshwater without fish protection requirements or freezing conditions, a pre-built screen can be appropriate. For anything larger, any application with regulatory requirements, any site with brackish water or freezing conditions, or any revenue-dependent application: custom engineering is strongly recommended.
Does ADENCO provide installation support?
Yes. Every custom screen delivery includes an installation guide specific to your site, detailed connection drawings, and remote engineering support. For complex or large projects, on-site supervision is available.
References
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PowerSpout. "Coanda 2 Full Intake Screen." Retrieved April 2026, from https://www.powerspout.com/products/coanda2-full-intake-screen
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"DIY Coanda Effect Micro Hydro Intake." EcoSnippets. Retrieved April 2026, from https://www.ecosnippets.com/alternative-energy/diy-coanda-effect-micro-hydro-intake/
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Wahl, T.L. (2003). Design Guidance for Coanda-Effect Screens. U.S. Bureau of Reclamation, Research Report R-2003-03. Denver, CO.
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"Susceptibility of Type 304/304L and 316/316L Austenitic Stainless Steels to Chlorides in Cooling Water." Digital Refining. Retrieved April 2026, from https://www.digitalrefining.com/article/1002873/
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British Stainless Steel Association. "Selection of 316, 304, and 303 Types of Stainless Steels for Seawater Applications." Retrieved April 2026, from https://bssa.org.uk/bssa_articles/selection-of-316-304-and-303-types-of-stainless-steels-for-seawater-applications/
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UK Environment Agency. "Screening at Intakes and Outfalls: Measures to Protect Eel." Retrieved April 2026, from https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/1097095/
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Wahl, T.L. (2001). "Hydraulic Performance of Coanda-Effect Screens." Journal of Hydraulic Engineering, Vol. 127, No. 6, pp. 480–488. ASCE.
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Gebre, S. et al. (2014). "Performance of Coanda-Effect Screens in a Cold Climate." Journal of Cold Regions Engineering, Vol. 28, No. 4. ASCE.
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Daly, S.F. et al. (2023). "Prevention of Water Intake Blockage by Ice during Supercooling Events." Journal of Cold Regions Engineering, Vol. 37, No. 1. ASCE.
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USBR. "Coanda-Effect Screens Software & Design Tools." Retrieved April 2026, from https://usbr.gov/tsc/techreferences/computer%20software/software/coanda/
Published by ADENCO: Advanced Engineering Coanda Intake Screens. Custom, project-specific engineering is ADENCO's core capability. Every screen we deliver is designed for your exact site conditions, manufactured to precision tolerances, and supported with full engineering documentation. Request a consultation to start your custom design.